Workpiece treating apparatus

ABSTRACT

A workpiece treating apparatus includes a slatted barrel for holding the workpieces during rotation of the barrel. A draw bar is disposed generally parallel to the barrel slats and has workpiece engaging pawls thereon. The draw bar is mounted for oscillatory movement and for rotational movement about its own axis so that the pawls can engage the workpieces and pull them forward in the barrel and can then be disengaged from the workpieces whereby the pawls may return to their original position.

United States Patent [1 1 Carpenter et al.

[ July 31, 1973 WORKPIECE TREATING APPARATUS [75] Inventors: James HughCarpenter, Hagerstown,

Md.; Harper Willard Good, Waynesboro, Pa.

[73] Assignee: The Carborundum Company,

Niagara Falls, N.Y.

[22] Filed: May 15, 1972 [21] Appl. No.: 253,381

Related U.S. Application Data [63] Continuation of Ser. No. 65,465, Aug.20, 1970,

abandoned.

[52] U.S. Cl. 51/15, 51/215 AR [51] Int. Cl. B24c 9/00 [58] Field ofSearch 5l/9, l4, 15, 215 R; 134/144 [56] References Cited UNITED STATESPATENTS 2,154,878 4/1939 Tumbull 51/14 X 2,204,636 6/1940 Tumbull 51/14X 2,565,341 8/1951 Arispe 51/15 2,918,071 12/1959 Umbricht 134/1443,517,465 6/1970 Freeman 51/15 X 3,534,504 10/1970 Carpenter 51/153,626,641 12/1971 Powell 51/9 Primary Examiner-Donald G. KellyAttorney-David E. Dougherty et al.

[57] ABSTRACT A workpiece treating apparatus includes a slatted barrelfor holding the workpieces during rotation of the barrel. A draw bar isdisposed generally parallel to the barrel slats and has workpieceengaging pawls thereon. The draw bar is mounted for oscillatory movementand for rotational movement about its own axis so that the pawls canengage the workpieces and pull them forward in the barrel and can thenbe disengaged from the workpieces whereby the pawls may return to theiroriginal position.

14 Claims, 13 Drawing Figures PATENIEU JUL 31 7 SHEEI 2 [1F 6 PATENTEDJUL 3 1 7 SHEH 3 [IF 6 WORKPIECE TREATING APPARATUS This is acontinuation, of copending application Ser. No. 65,465, filed Aug. 20,1970 now abandoned.

BACKGROUND OF INVENTION The device of copending application Ser. No.553,183, tiled May 26, 1966, represents a significant advancement in thehigh volume cleaning of castings, such as automobile cylinder heads,engine blocks, and the like. This axi-flow device utilizes blastcleaning to remove cast sand and scale from the castings. High volumeproduction is accomplished through the use of a rotatable barrel whichis made in skeletal form by a plurality of longitudinal slats which areso arranged as to hold the castings druing rotation of the barrel sothat the castings and barrel rotate together. In this manner, all of thesurfaces of the castings are exposed to the blast cleaning operation.

Due to the many depressions and deep openings in such parts as castings,thorough cleaning becomes a problem. When castings are conveyed thru theblast area by confining them between long wearing alloy bars androtating the castings under the blast stream, as with conventionalaxi-flo machines, usually the ends of the castings are, to some degree,shielded by adjacent castings. Many methods have been devised forseparating the workpieces while they are being blast cleaned, thusexposing the ends to the full application of the blast streams. Some ofthese systems are too intricateto withstand constant exposure to shot orgrit blasting without frequent breakdowns or jamming. Other systems arein the way of the blast streams and blind certain areas of the castingsagainst effective cleaning.

Various attempts to separate the workpiece are disclosed in the US. Pat.No. 3,626,641, issued Dec. 14, 1970 and in US. Pat. No. 3,534,504,issued Oct. 20, 1970. Additionally US. Pat. Nos. 2,918,071 and 3,517,465are of interest to the general field of this invention.

SUMMARY OF THE INVENTION 'An object of this invention is to provide ,aworkpiece treating apparatus which overcomes the above disadvantages.

In accordance with this invention the workpiecetreating apparatuscomprises a slatted barrel for holding the workpieces during rotation ofthe barrel. A draw bar is disposed generally parallel to the barrelslats and has workpiece engaging pawls thereon. The draw bar is mountedfor oscillatory movement and for rotational movement about its own axisso that the pawls can engage the workpiece and pull them forward in thebarrel and can then be disengaged from the workpieces whereby the pawlsmay return to their original position.

Advantageously, the draw bar is mounted for rotation with the barrel andis interlocked with the barrel rotation drive for synchronization of therotational and oscillatory movements. The oscillatory means may includedwell periods at the end of each forward and return stroke so that thepawl may move into and out of engagement with the workpieces duringthese dwell periods.

In an advantageous form of this invention, a stationary cam may bemounted on a central shaft which is coaxial with the axis of rotation ofthe barrel. A follower is connected to the draw bar and rides on the camtrack of the cam during rotation of the barrel to effectuate therotational movement of the draw bar about its own axis.

Another feature particularly noteworthy is the inclusion of a safetymechanism 'to prevent damage should the pawls fail to properly engagethe workpiece by, for example, striking a workpiecerather than moving inback of it. The safety mechanism may include an arm rigidly connected tothe draw bar with a spring housing or chamber arranged on the follower.Resilient means or a spring is disposed in the chamber and reactsagainst the arm to transmit the rotational movement of the follower tothe draw bar during normal operation. If, however, the pawls shouldstrike the workpiece during abnormal operation, the follower wouldcontinue to rotate but the spring would not cause the draw bar to rotatesince the spring would be compressed by the non-rotating arm.

THE DRAWINGS FIG. 1 is a side elevation view partly in section of anapparatus in accordance with this invention in one stage of operation;

FIG. 2 is a side view similar to FIG. 1 in a different phase ofoperation;

FIG. 3 is a plan view of the apparatus shown in FIG.

FIG. 4 is an elevation view of a portion of the apparatus shown in FIGS.1-3;

FIG. 5 is a schematic elevation view of the cam mechanism utilized inthe apparatus shown in FIGS. l-4;

F IG. 6 is a cross-sectional view taken through FIG. 4 along the line6-6;

FIGS. 79 are end elevation views similar to FIG. 6, but in differentphases of operation;

FIGS. 10-11 are end elevation views of the safety mechanism utilized inthis invention in different phases of operation;

FIG. 12 is a plan view partly in section of the safety mechanism shownin FIG. 10; and

FIG. 13 is an elevation view of an end pawl utilized with thisinvention.

DETAILED DESCRIPTION FIGS. 1-2 show an apparatus 10 which includes ahousing 12 having an axial flow barrel 14 therein. Barrel 14 is of thesame general construction as the barrel shown and described in copendingapplication Ser. Nos. 553,183, filed May 26, 1966; US. Pat. No.3,534,504, dated Oct. 20, 1970; and US Pat. No. 3,626,641, dated Dec.14, 1971, the details of which are incorporated herein by referencethereto. In general the apparatus includes an endless conveyor 16 whichtransports workpieces such as castings 18 to the open end of barrel 14.Any suitable feed device may be used. For example a cradle-walking beamarrangement 20 may dispose a casting at the barrel entrance and a pawl36 may pull the castings one at a time into the barrel. Barrel 14 is ofskeletal form and includes support drum sections 22, 23 which arespanned by elongated slats 24. The particular arrangement of slats 24 issuch that the slats generally conform to the shape of the workpieces 18so as to hold the workpieces during rotation of the barrel whereby thebarrel and workpieces rotate together. Any suitable drive means 26 maybe utilized for rotating the barrel. Barrel 14 continuously rotates inone direction. The parts are moved through the barrel, as laterdescribed, and during the rotation are exposed to the blast streamsprojected by conventional centrifugal throwing wheels 28. After theworkpieces are cleaned they are deposited upon endless conveyor 30 atthe discharge end of the barrel.

The present invention is particularly concerned with the means forspacing and conveying the workpieces through the barrel so as to exposethe ends of the workpiece, as well as the other surfaces, to the blaststream to maximize the cleaning action. In general, this arrangementincludes a draw bar 32 disposed generally parallel to slats 24. The drawbar rotates with the barrel and is supported for longitudinal movementin any suitable manner, by for example, sliding in faces 27 of drumsections 22, 23. The draw bar is capable of longitudinally oscillatingin forward and return strokes by means of oscillating mechanism 34. Aplurality of pawls 36 are mounted on the draw bar 32 in such a mannerthat during a dwell period at the end of a return stroke of the drawbar, the draw bar and its pawls rotate about the draw bar axis so thateach pawl engages a workpiece. The draw bar and engaged pawls thenrotate with the barrel during the cleaning action to maintain theworkpiece spacing. The draw bar is then moved in a forward stroke by adistance equal to the length of one workpiece plus the space betweenadjacent workpieces so that the workpieces are indexed through thebarrel with the end workpiece being discharged while a new workpiece ispulled into the barrel.

Oscillating mechanism 34 is of any suitable construction and may, forexample, be a unit which is commercially available. Since the specificdetails of the oscillating mechanism do not form a part of thisinvention, it will be described only where necessary for anunderstanding of the invention. The oscillating drive is interlockedwith barrel drive shaft 38 so as to synchronize the rotational movementof the barrel with the oscillatory movement of draw bar 32. Accordingly,the rate of cleaning can be varied without regard to other adjustments.

The oscillating mechanism 34 imparts a gradually accelerated axialmovement and a gradually decelerated movement at the end of each stroke,while dwell periods are provided between the strokes. Additionally, theaxial movement includes a rapid return stroke.

As shown in FIGS. 1-3 oscillating mechanism 34 includes a bifurcatedsupport arm 40 having a yoke end 42. A pair of bars 44 are connected tothe yoke at one end and at their other end are connected to sleevemember 46. Sleeve 46 has an offset arm 48 and terminates in a furthersleeve member 50, which in turn is rigidly but rotatably connected todraw bar 32. A central shaft 52 is mounted on the outer end of barrel 14co-axial with the axis of rotation of the barrel. Shaft 52, however,does not rotate or move longitudinally and is also suspended from anysuitable support 54. Shaft 52 has the dual function of providing a meansupon which a stationary cam 56 may be mounted (as later described) andof providing guide means for longitudinally movable sleeve member 46.

FIG. shows an elevation view of the stationary cam ary, the rotationalmovement of draw bar 32 caused by its connection to barrel 14 causesfollower 64 to also rotate. During the movement of follower 64 thefollower roller 62 rides in cam track 60 which in turn causes draw bar32 to rotate about its own axis at predetermined cam track positions. Asshown in FIG. 5 the cam track 60 includes a pair of dwell arcs A and Bwhich in the illustrated embodiment are and respectively. Between thearcs A and B are active arcs C and D. When follower roller is in the areA there is a dwell in that draw bar 32 does not rotate about its ownaxis and the pawls remain disengaged from the workpiece. As the follower62 continues to move and is in are C, draw bar 32 is caused to rotate sothat the pawls move toward engagement in back of the workpiece. Thisrotation continues until are 8 is reached. Arc B represents anotherdwell period when there is no rotation of draw bar 32, whereupon thepawls remain engaged with the workpieces. When the follower roller 62 isin are D, draw bar 32 again rotates to disengage the pawls from theworkpieces. FIG. 5 also illustrates the positions assumed by the drawbar and the follower at the end of the forward stroke of the draw bar asdesignated by the arrow B and at the end of the draw bar return strokeas designated by the arrow F.

FIGS. 6-9 show the draw bar and pawl arrangement during different phasesof operation. As illustrated in FIG. 6, the pawl 36 is moving intoengagement behind the workpiece 18. This movement takes place during thedwell period of the oscillating drive 34 at the end of the returnstroke.

FIG. 7 shows a subsequent stage of operation wherein the pawl 36 isfully engaged with the workpiece 18. When the various parts are in thisposition, the barrel l4 continues to rotate and the workpieces 18 aresubjected to the primary blast treatment. Oscillating drive 34 thereuponpulls draw bar 32 forward while another workpiece is being inserted intothe barrel.

FIG. 8 shows the positions of the various parts when the last workpiece18 is about to be discharged from the barrel. FIG. 9 illustrates theposition of the parts when the workpiece is being discharged and thepawl 36 is moving out of engagement by the rotation of draw bar 32. Thiscycle is continuously repeated with the rotation taking place in thesame direction.

As also shown in FIG. 9, the falling workpieces 18 are received on adischarge conveyor 30. FIGS. 1 and 4 most clearly show the provisionsmade to permit the cleaned workpiece to be discharged by simply fallingfrom the barrel onto conveyor 30. As illustrated therein, the dischargedrum section 23 includes an opening 25. In this drum section 23 are aset of slats 24a which are shorter than the remaining slats 2417 orterminate upstream from slats 24b thereby creating an opening inregistry with opening 25 at the discharge end of the barrel.

The pawls 36 may have any suitable construction. Generally, however,each pawl includes a sleeve 66 which fits around draw bar 32 and isrigidly secured thereto by key 68. (See FIGS. 1, 2, and 6.) A shank 70extends from sleeve 66 and terminates in a hooklike contact surface 72.In this manner, there is a minimum blinding of the workpieces resultingfrom the pawls.

In general a single pawl is disposed in back of every workpiece toassure a proper indexing of the workpieces. When the draw bar isreciprocated, however, clearance difficulties arise adjacent the slatsupporting faces 27 in the drums 22,23 and special provisions must bemade. In this respect a separate pawlcould not be provided adjacentthese faces-27 since the reciprocating draw bar would cause the pawls tostrike the faces 27. FIG. 13 shows the construction of pawls 36a whichare designed to overcome these difficulties. As illustrated therein, theworkpiece engaging surface 72 includes an offset extension 74 which alsoterminates in a workpiece engaging surface 76. workpiece engagingsurface 76 is so arranged as to fit into an opening in a workpiece 18awhile engaging surface 72 pushes against the preceding adjacentworkpiece 18b. Accordingly, the same pawl 36a simultaneously pushesworkpiece 18b and pulls succeeding workpiece 18a. Such pawls 36a may beprovided wherever there are clearance difficulties.

The pawls 36 (or 36a) are particularly advantageous since these areheavy durable pawls which are able to withstand the conditions inside ablast area. The pawls which communicate with the workpiece have a smallcontact area and stand away from the workpiece so as to avoid blindingof certain areas of the workpiece during blast cleaning. It is alsonoteworthy that the main parts of the mechanism for pulling theworkpieces are located outside of the blast area, thus providing forprotection, access and proper lubrication. Moreover, the spacing betweenthe workpieces which facilitates the end blast cleaning is maintainedthroughout the movement of the workpieces in the blast area.

FIGS. -12 show another aspect of the invention relating to the safeguard or safety mechanism 78. Inclusion of this mechanism is animportant feature. If, for any reason, one or more of the castings beingtreated should be out of position, under such circumstances the engagingpawl or pawls would strike the workpiece or workpieces. The safetymechanism prevents jamming, damage or breakage which would otherwiseoccur. In this respect, the safety mechanism prevents the full force ofcam 56 from being transmitted to draw bar 32. In the illustratedembodiment, follower 64 includes a chamber 80 which houses a spring 82.Safety arm 84 is located at the end of chamber 80 and is rigidlyconnected to draw bar 32. Spring 82 reacts against arm 84 so that undernormal conditions the movement of the follower is transmitted by spring82 to safety arm 84. Thus as follower 64 rotates arm 84 is also causedto rotate. Since arm 84 is rigidly connected to draw bar 32, therotational movement is transmitted to the draw bar whereupon pawls 36also rotate. FIG. 10 shows the position assumed by the various elementsduring normal operation. As also illustrated therein, a tensioning screw86 is provided to adjust the tension of spring 82.

FIG. II shows the relative positions of the various elements duringabnormal operating conditions. As indicated therein, pawl 36 hascontacted the workpiece 18 rather than sliding behind it. Since thebarrel 14 continues to rotate, however, follower 64 also continues torotate. As follower 64 rotates spring 82 is compressed by arm 84 becausethe arm, its draw bar, and the pawl can no longer rotate. Thus follower64 is permitted to continue rotating without causing jamming or breakageby otherwise transmitting the full force of the rotation to the draw bar32. If desired, the entire apparatus 10 may be automatically stopped by,for example, the actuation of suitable switching (not shown) to eitherset off an alarm or to automatically inactivate the various drives. Inthis respect an arm 90 may be disposed at the end of mechanism 78parallel to its end surface. During abnormal operation the arm 90 wouldbecome tilted and would contact a stationary switch 92 to initiate thedesired control operation. I

What is claimed is: I

1. A workpiece treating apparatus comprising a barrel made of skeletalform, said barrel being formed from a plurality of spaced longitudinalslats for holding a plurality of workpieces during rotation of saidbarrel, means for rotating said barrel aboutan axis of rotation, a drawbar disposed generally parallel to said slats, said draw barbeingmounted for longitudinal movement backward and forward generallyparallel to the axis of rotation, workpiece engaging means fixed on saiddraw bar, means for radially moving said workpiece engaging means to aposition for engaging said engaging means with the workpieces and toanother position for disengaging said engaging means with theworkpieces, axially oscillating means for moving said draw bar forwardand backward, and means for synchronizing said moving means and saidoscillating means for causing said engaging means to be engaged with theworkpieces on a forward movement and to cause said engaging means to bedisengaged from the workpieces on a backward movement of said draw bar.

2. An apparatus as set forth in claim 1 wherein said draw bar isconnected to said barrel for rotation with said barrel.

3. An apparatus as set forth in claim 2 wherein said barrel rotationmeans and said oscillating means are interlocked for synchronization ofthe rotational movement of said barrel and oscillatory movements.

4. An apparatus as set forth in claim 2 wherein said oscillating meanshas a dwell period at the end of each forward and backward movement.

5. An apparatus as set forth in claim 4 wherein said means for movingsaid workpiece engaging means includes cam means for causing saidworkpiece engaging means to selectively engage and disengage theworkpieces during the dwell periods of said oscillating means.

6. An apparatus as set forth in claim 5 wherein said cam means includesa stationary cam mounted substantially coaxial with the axis of rotationof said barrel, and a follower connected to said draw bar and riding onthe cam track of said cam.

7. An apparatus as set forth in claim 6 wherein said cam is mounted on astationary shaft which is coaxial with the axis of rotation of saidbarrel, said central shaft further comprising guide means for saidoscillating means. I

8. An apparatus as set forth in claim 6 including a safety mechanismmounted on said draw bar for preventing said draw bar from rotatingabout its own axis when said workpiece engaging means is unable to beproperly disposed against a workpiece.

9. An apparatus as set forth in claim 8 wherein said safety mechanismincludes an arm rigidly connected to said draw bar, a chamber connectedto said follower,

- and resilient means in said chamber reacting against .said arm totransmit the rotational movement of said 10. An apparatus as set forthin claim 9 including inactivating means for inactivating said apparatusupon compression of said resilient means.

1 1. An apparatus as set forth in claim 4 wherein said workpieceengaging means includes a plurality of 5 pawls, each of said pawlshaving a shank rigidly connected to said draw bar, and a workpieceengaging surface at the free end of said shank.

12. An apparatus as set forth in claim 11 wherein at whereby the samepawl can simultaneously push one workpiece and pull an adjacentworkpiece.

13. An apparatus as set forth in claim 2 wherein said plurality of slatsinclude a set of slats which terminate upstream from to remaining slatsto create an open area throughwhich a workpiece may fall, and adischarge conveyor disposed under said open area.

14. An apparatus as set forth in claim 2 wherein said draw bar ismounted for rotation about its own axis and said means for moving saidworkpiece engaging means rotates said draw bar to a position forengaging said engaging means with the workpieces and to another positionfor disengaging said engaging means with the workpieces.

* I l i i

1. A workpiece treating apparatus comprising a barrel made of skeletal form, said barrel being formed from a plurality of spaced longitudinal slats for holding a plurality of workpieces during rotation of said barrel, means for rotating said barrel about an axis of rotation, a draw bar disposed generally parallel to said slats, said draw bar being mounted for longitudinal movement backward and forward generally parallel to the axis of rotation, workpiece engaging means fixed on said draw bar, means for radially moving said workpiece engaging means to a position for engaging said engaging means with the workpieces and to another position for disengaging said engaging means with the workpieces, axially oscillating means for moving said draw bar forward and backward, and means for synchronizing said moving means and said oscillating means for causing said engaging means to be engaged with the workpieces on a forward movement and to cause said engaging means to be disengaged from the workpieces on a backward movement of said draw bar.
 2. An apparatus as set forth in claim 1 wherein said draw bar is connected to said barrel for rotation with said barrel.
 3. An apparatus as set forth in claim 2 wherein said barrel rotation means and said oscillating means are interlocked for synchronization of the rotational movement of said barrel and oscillatory movements.
 4. An apparatus as set forth in claim 2 wherein said Oscillating means has a dwell period at the end of each forward and backward movement.
 5. An apparatus as set forth in claim 4 wherein said means for moving said workpiece engaging means includes cam means for causing said workpiece engaging means to selectively engage and disengage the workpieces during the dwell periods of said oscillating means.
 6. An apparatus as set forth in claim 5 wherein said cam means includes a stationary cam mounted substantially coaxial with the axis of rotation of said barrel, and a follower connected to said draw bar and riding on the cam track of said cam.
 7. An apparatus as set forth in claim 6 wherein said cam is mounted on a stationary shaft which is coaxial with the axis of rotation of said barrel, said central shaft further comprising guide means for said oscillating means.
 8. An apparatus as set forth in claim 6 including a safety mechanism mounted on said draw bar for preventing said draw bar from rotating about its own axis when said workpiece engaging means is unable to be properly disposed against a workpiece.
 9. An apparatus as set forth in claim 8 wherein said safety mechanism includes an arm rigidly connected to said draw bar, a chamber connected to said follower, and resilient means in said chamber reacting against said arm to transmit the rotational movement of said follower to said draw bar during normal operation and to be compressed by said arm during abnormal operation whereby said draw bar does not rotate with said follower during abnormal operation.
 10. An apparatus as set forth in claim 9 including inactivating means for inactivating said apparatus upon compression of said resilient means.
 11. An apparatus as set forth in claim 4 wherein said workpiece engaging means includes a plurality of pawls, each of said pawls having a shank rigidly connected to said draw bar, and a workpiece engaging surface at the free end of said shank.
 12. An apparatus as set forth in claim 11 wherein at least one of said pawls includes an offset portion extending from its workpiece engaging surface, and a further workpiece engaging surface on said offset portion whereby the same pawl can simultaneously push one workpiece and pull an adjacent workpiece.
 13. An apparatus as set forth in claim 2 wherein said plurality of slats include a set of slats which terminate upstream from to remaining slats to create an open area through which a workpiece may fall, and a discharge conveyor disposed under said open area.
 14. An apparatus as set forth in claim 2 wherein said draw bar is mounted for rotation about its own axis and said means for moving said workpiece engaging means rotates said draw bar to a position for engaging said engaging means with the workpieces and to another position for disengaging said engaging means with the workpieces. 